1. Field of the Invention
The nitidulid beetles, such as Carpophilus freemani, C. hemipterus, and C. lugubris, are significant pests of fruits and vegetables, as well as vectors of pathogens to trees and vectors of mycotoxin-producing fungi to corn. This invention relates to organophosphorus insecticides that synergistically increase the attractancy of pheromones from these insects. Thus, these organophosphorus compounds not only kill the insects but they also extend the life of pheromone-containing baits and decrease the amount of pheromone needed.
2. Description of the Prior Art
Insect-produced volatiles (e.g., pheromones) and host plant odors (e.g., kairomones) may facilitate location of conspecifics for mating and orientation to acceptable host plants for feeding and oviposition. It is known that in several, but not all, insect species (e.g., bark beetles) pheromones and a few specific plant odors, such as monoterpenes, may act in synergy, each enhancing the attraction of the other [Borden, In Insect Communication, T. Lewis, ed., Academic Press, New York, p. 123 (1984)].
Carpophilus hemipterus (L.) (Coleoptera: Nitidulidae) is a worldwide pest attacking agricultural commodities such as ripe and dried fruit, corn, wheat, oats, rice, beans, nuts, peanuts, cotton seed, copra, spices, sugar, honey, and other materials [Hinton, A Monograph of the Beetles Associated with Stored Products, Jarrold and Sons, Norwich, U.K., 443 pp. (1945)]. It is also able to vector microorganisms responsible for the souring of figs (Hinton, supra) and fungi which contaminate corn and produce mycotoxins [Wicklow et al., In NC-151, 1987: Annual Progress Reports from Participating Laboratories, pp. 31-32 (1988)].
The dusky sap beetle, Carpophilus lugubris Murray (Coleoptera: Nitidulidae) is distributed from Brazil through Central America [Parsons, Harvard Univ. Museum Comp. Zool. Bull. 92: 121-278 (1943)] and probably throughout the United States [Sanford, Observations on the biology and control of the dusky sap beetle, Carpophilus lugubris Murray, infesting sweet corn in Illinois, Univ. of Illinois, Urbana, 54 pp. (1958)]. It is found in ripe and decomposing fruit and vegetables [Sanford et al., Proc. North Central Br. Entomol. Soc. Am. 18: 39-43 (1963)], trees infected with oak wilt [Dorsey et al., Plant Dis. Rep. 37: 419-420 (1953); Norris, Plant Dis. Rep. 37: 417-418 (1953)], and poultry manure [Pfeiffer et al., Environ. Entomol. 9: 21-28 (1980)]. It is probably most important as a pest of sweet corn [Connell, Nitidulidae of Delaware, Univ. of Delaware Agric. Exper. Sta. Tech. Bull. #318, 67 pp. (1956); Sanford, supra; Connell, J. Econ. Entomol. 68: 279- 280 (1975); Tamaki et al., J. Entomol. Soc. Brit. Columbia 79: 3-8 (1982)], and can cause large amounts of corn to be rejected at canneries [Luckman et al., Proc. North Central Br. Entomol. Soc. Am. 14: 81-82 (1959)]. In addition, it appears to be a vector of oak wilt [Dorsey et al., supra; Norris, supra; Appel, J. Econ. Entomol. 79: 1276-1279 (1986)], and mycotoxin-producing fungi that contaminate corn [Wicklow et al., supra]. Although tight-husked corn can provide some control, this may be defeated when corn earworms or other insects provide entry holes [Connell, supra (1956); Tamaki et al., supra]. However, in many cases these insects are able to enter the ears without assistance [Connell, supra (1956); Tamaki et al., supra]. The loose-husked varieties of dent (field) corn adopted in association with the use of mechanical harvesting promote ready entry sites for these insects [Connell, supra (1956)].
Carpophilus freemani Dobson infests sweet corn [Sanford et al., supra] and corn seed and corn meal [Connell, supra (1975)]. It is a principal pest of figs [Smilanick et al., Proc. Calif. Fig Inst. Res. Meet. 1976: 27-41 (1976)] and the principal vector of Ceratocystis canker of stone fruits including almonds, prunes, peaches, and apricots [Moller et al., Phytopathology 59: 938-942 (1969)].
Field traps have been used to monitor or attempt to control these and other nitidulid species, and much research has gone into trap baits. Fermenting fig paste has been used as a trap bait for C. hemipterus [Obenauf et al., Proc. Calif. Fig Inst. Res. 1976: 61-94 (1976)]. Smilanick et al., [J. Chem. Ecol. 4: 701-707 (1978)] determined that a 1:1:1 mixture of acetaldehyde, ethyl acetate, and ethanol was an even more effective bait for C. hemipterus than fig paste, but trap catches were still relatively small, given the huge beetle populations. Due to the low activity of 16 other host volatiles tested, Smilanick et al. [supra (1978)] concluded that C. hemipterus "appears to use a restricted number of olfactory stimuli to locate suitable hosts." Previously reported methods of monitoring C. lugubris have been of limited effectiveness. It is well known that these insects can be attracted by fermenting baits [Luckman, supra]. Specific methods include using freshly sawn oak or maple blocks in combination with vinegar and fungi [Neel et al., J. Econ. Entomol. 60: 1104-1109 (1967); Dorsey et al., J. Econ. Entomol. 49: 219-230 (1956)]. However, the attractiveness of these baits varies over time due to changes in fermentative activity [Neel et al., supra]. Previously reported methods of attracting C. freemani are also of limited effectiveness. The only reported method specifically describing C. freemani attraction is that of Smilanick et al. [supra (1978)]. The response of C. freemani to Smilanick's 3-component mixture appeared to be relatively poor compared to that of C. hemipterus, and not significantly different from fig paste or controls. Alm et al. [J. Econ. Entomol. 78: 839-843 (1985); ibid. 79: 654-658 (1986)] demonstrated that esters such as propyl propionate and butyl acetate were effective baits for Glischrochilus quadrisignatus, another economically important nitidulid, but did not compete with banana. In nature, these chemicals exist in the host plant, are produced by microorganisms which have established on the plants, or both.